Two top U.S. intelligence officials say the global financial crisis, population growth, and the potential for international conflict pose the greatest threats to the U.S. and world stability.

National Intelligence Director Dennis Blair told the Senate Armed Services Committee Tuesday that the U.S. does not face a direct military threat in the near future. But he said that the addition of another one billion people to the world's population by 2025 will put pressure on the global environment as well as on food, water and energy supplies.

He told senators that the Somali extremist group al-Shabab, which conducts almost daily attacks in Somalia, is preparing to formally merge with al-Qaida - a move that would strengthen al-Qaida's foothold in east Africa.

Maples said the security situation in Afghanistan continued to deteriorate last year, with the use of roadside bombs there more than doubling over 2007 and insurgent attacks increasing by 55 percent.

He also warned of a potential for conflict among major nation-states, which he said could intersect vital U.S. interests.

Blair said that the U.S. will be expected to lead multilateral efforts to solve global problems, including terrorism, arms proliferation and human rights abuses.

He also warned that terrorism will also be a growing threat to cyberspace as terrorists expand their use of tactics and techniques. He said the U.S. has to keep strengthening its cyber defenses.

Blair and Maples both called for restoring strong U.S. economic growth, keeping its scientific and technological edge and maintaining strong defense intelligence.